A biofilm is a group of microorganisms in which cells stick to each other on a surface. These adherent cells are frequently embedded within a self-produced matrix of extracellular polymeric substance (EPS). Biofilm EPS is a polymeric conglomeration generally composed of extracellular DNA, proteins, and polysaccharides. Biofilms may form on living or non-living surfaces and can be prevalent in natural, industrial, and hospital settings (Hall-Stoodley et al., Lear). The microbial cells growing in a biofilm are physiologically distinct from planktonic cells of the same organism, which, by contrast, are single-cells that may float or swim in a liquid medium.
Nearly every species of microorganism, not only bacteria, fungi, and archaea, have mechanisms by which they can form biofilms by adhering to surfaces and to each other. Biofilms can form on virtually any non-shedding surface in a non-sterile aqueous or humid environment.
Biofilms have been found to be involved in a wide variety of microbial infections in the body, by one estimate 80% of all infections (NIH). Infectious processes in which biofilms have been implicated include urinary tract infections, sinusitis, catheter infections, middle-ear infections, formation of dental plaque (Rogers), gingivitis (Rogers), infections on contact lenses (Imamura et al.), endocarditis, infections in cystic fibrosis, skin infections (Davis et al.), and infections of implanted devices or permanent indwelling devices such as joint prostheses, prosthetic heart valves, catheters, and intrauterine devices (Lewis, Parsek et al., Auler et al., Donlan et al.).
Biofilms confer microorganisms resistance to antimicrobial agents, whether these antimicrobial agents are antibiotics, disinfectants, or germicides (Donlan et al.). Mechanisms responsible for this resistance is thought to include one or more of the following: (i) delayed penetration of the antimicrobial agent through the biofilm matrix, (ii) altered growth rate of biofilm organisms, and (iii) other physiological changes due to the biofilm mode of growth (Donlan et al.).
Enzymes that degrade biofilm matrix polymers have been shown to inhibit biofilm formation, detach established biofilm colonies, and render biofilm microorganisms sensitive to antimicrobial agents (Kaplan).
Enzymes that have enhanced activity in preventing biofilm formation or degrading existing biofilms are needed.